Pneumatic inflation system for tyre-changing machines

ABSTRACT

The improvement in a pneumatic inflation system for tyre-changing machines ( 1 ) provides that between a pressurised fluid supply organ ( 2 ) and a delivery organ ( 3 ) of the fluid, at least one limiter valve ( 4 ) of the fluid supply is located, which intercept valve ( 4 ) can limit the fluid delivery to at least two maximum pressure values, which values are different one to another and which are alternatively selectable by a user.

DESCRIPTION

[0001] The invention relates to an improvement in a pneumatic inflation system for tyre-changing machines.

[0002] At present, inflation systems in tyre-changing machines for motor vehicles and the like are provided with an inflation pressure limiter device which limits the pressure of the compressed air to a predetermined maximum value which is preset by the manufacturer, with no distinction made for the types of tyres.

[0003] This value depends on the type of tyres to be inflated with certain machines. In other words, tyre-changing machines are built as dedicated to operations on tyres for both motor cars and “derivative” vehicles, while other machines are dedicated to heavy industrial vehicle tyres.

[0004] The drawback deriving from the prior art consists in the fact that the tyre operatives in both cases, during the inflating operations following tyre mounting, can introduce high-pressure air, sometimes well above the maximum safety rating levels set by the manufacturers, in some cases even exceeding what is allowed by existing standards, for example UNI standards.

[0005] This possibility, caused sometimes by the need to complete operations rapidly, can lead to dangerous damage to the tyre structure, both in car tyres and “derivative” vehicle tyres, as anomalous deformation thereof can result.

[0006] To add to this, the structural differences of tyres of these “derivative” vehicles with respect to motor car tyres are on the one hand minimal as far as dimensions and weights are concerned, but can be considerable in relation to the structure and capacity for transporting goods of the tyres fitted on the vehicles themselves. These differences in vehicle use destination necessarily lead to different tyre inflation pressures.

[0007] The technical aim of the present invention is to eliminate the above-cited drawback in the prior art by providing an improvement in the system for tyre inflation in tyre-changing machines, which improvement enables tyre operatives to work with rapidity and in maximum safety conditions, as well as to avoid damage to tyres during the inflation operations, whether those tyres are fitted on motor cars or vehicles which are alike but which have different use destinations.

[0008] In the ambit of this technical aim, a further aim of the present invention is to achieve the above-described operation with a simple structure, easy to actuate in practice and, especially, inexpensive. This aim and more besides are all attained by the improvement in a pneumatic inflation system for tyre-changing machines, which is characterised in that a supply intercept limiter valve is interpositioned between a pressurised fluid supply organ and a delivery organ of the pressurised fluid; the valve having at least two different maximum pressure values, which values are selectable on the part of a user.

[0009] Further characteristics and advantages of the present invention will better emerge from the detailed description that follows, of a preferred but not exclusive embodiment of an improvement in a pneumatic tyre inflation system of a tyre-changing machine, here illustrated in the form of a non-limiting example in the enclosed figures of the drawings, in which:

[0010]FIG. 1 is a perspective view of a conventional tyre-changing machine, provided with the improvement in the pneumatic inflation system according to the invention;

[0011]FIG. 2 is a detailed view in enlarged scale of the limiter valve constituting the invention, in a first embodiment, for intercepting delivery of pressurised air between two values, settable with continuity between a lower value and a higher value and vice versa;

[0012]FIG. 3 is a partial detailed view in enlarged scale of the limiter valve of the invention, in a second embodiment thereof, for intercepting pressurised air at two alternatively settable values.

[0013] With reference to the figures of the drawings, 1 denotes in its entirety a tyre-changing machine provided with a pneumatic inflation system, denoted in the figures of the drawings by piping

[0014] In the improvement of the invention, a limiter valve 4 is interposed between an organ for pressurised fluid supply, in this case air, which organ may be a tank provided on the machine 1 or a source located in the room where the machine 1 is installed, and an air delivery organ 3, for example an attachment for tyre valves. The limiter valve 4 intercepts supply of the air at at least two maximum pressure values, which values are different one from another and selectable alternatively by a user.

[0015] The limiter valve 4 can be made in at least two versions. In a first version, illustrated in FIG. 2, the maximum pressure values can be selected continuously, i.e. setting both the two maximum pressure values and the intermediate values between the lower value and the upper value, and vice versa.

[0016] In a second version of the limiter valve 4, illustrated in FIG. 3, the maximum values, though set as in the first version, are selectable discontinuously, i.e. either the lower maximum value or the higher maximum value can be selected, but intermediate values between the two are not passed through.

[0017] In the preferred embodiment of the improvement of the invention, the above-cited pressure values are respectively 4 bar for the lower maximum value and 6 bar for the upper maximum value.

[0018] These values enable tyre inflation for motor cars, with a delivery intercept threshold of compressed air set at 4 bar; while for “derivative” vehicles a delivery intercept threshold of compressed air is set at 6 bar.

[0019] Advantageously, the limiter valve 4 is provided in both versions with a handle 5 or 6 which can be gripped by the user for selecting the maximum pressure intercept value desired.

[0020] The limiter valve 4 is also optionally couplable functionally and synergically with a graduated observation pressure gauge 7.

[0021] The functioning of the invention is implicit from the foregoing description. Through the limiter valve 4, the user selects the maximum pressure that the compressed air can reach in inflating tyres 8, according to the type of tyres and also according to the tyre manufacturer's recommendations. If the tyre is mounted on a motor car, the operator selects the maximum value of 4 bar, while if the tyre is mounted on a derivative vehicle, the operator selects the maximum value of 6 bar. The operator then proceeds to inflating the tyre as usual, with the security of knowing that the intercept limiter valve 4 will interrupt delivery of air before the pressure goes above one which could damage the tyre 8 structure. The way in which the described invention reaches the set aims has been proved.

[0022] All details can be substituted by technically equivalent ones. In practice, all materials used, as well as the shapes and sizes of the parts used, may be of any kind according to needs.

[0023] The invention is susceptible to modifications and variations, all of which fall within the ambit of protection of the following claims. 

1). An improvement in a pneumatic inflation system for tyre-changing machines (1) characterised in that, located between a pressurised fluid supply source and a delivery organ (3) of the pressurised fluid, at least one intercepting limiter valve (4) of pressurised fluid delivery is comprised, the limiter valve (4) offering at least two maximum possible values of fluid pressure, which maximum values are different one from another and which are alternatively selectable by a user. 2) The improvement in a pneumatic inflation system for tyre-changing machines of claim 1, characterised in that the two maximum possible values are preset and are selectable continuously, from the lower of the two maximum possible values up to the higher of the two maximum values, and vice versa. 3) The improvement in a pneumatic inflation system for tyre-changing machines of claim 1, characterised in that the two maximum possible values are preset and are selectable discontinuously, the values being set at either the lower of the two maximum possible values or at the higher of the two maximum values, and vice versa. 4) The improvement in a pneumatic inflation system for tyre-changing machines of any one of the preceding claims, characterised in that the said two maximum possible values are preset, for the lower one, at a value comprised between 3.5 and 4.5 bar, and for the higher one, at a value comprised between 5.5 and 6.5 bar. 5) The improvement in a pneumatic inflation system for tyre-changing machines (1) of any one or more than one of the preceding claims, characterised in that the limiter valve (4) is provided with a handle (5, 6) for selecting between the lower value and the higher value and vice versa, the handle being grippable by a user. 6) The improvement in a pneumatic inflation system for tyre-changing machines (1) of claim 5, characterised in that the limiter valve (4) is provided with a graduated pressure gauge (7) for observation. 